Experimental investigation of link beams with perforated web section in eccentrically braced frames

Abstract

Eccentrically braced frame (EBF) system is one of the most effective lateral loads resisting systems for steel structures. In these systems, links are designed in such a way that they yield in shear not only to provide high ductility and rigidity but also to provide a high energy dissipation capacity. In particular, as the internal forces to be considered for the design of the members outside of the links must be calculated with the amplification factor based on the yielding of the links, the magnitude of the internal forces may become so large that they may not be met by the adjacent members. Therefore, it is challenging to develop an economic design for adjacent members and connections because of the high level of design loads obtained by the amplification factor. This paper studies the effect of the perforation arrangement in the web of shear link beams in eccentrically braced frames. Both experimental and numerical investigation were conducted to demonstrate the effectiveness of the link beam with slotted perforations in the web portion. Seven equivalent isolated link beam specimens with various slot-hole patterns were tested under quasi-static cyclic loading. The results of the study indicate that using slot-holes in the web portion reduces the link shear capacity significantly. The results also show that the failure mechanism of reduced link sections was controlled by fracture at end of the slot-holes and inelastic rotation capacities were varying between 0.025 rad and 0.065 rad depending on the slot-hole patterns.